Joomla websites, including Joomla 1.5 core and 2.5 core sites, have the error message called "JUser: :_load: Unable to load user with ID: 60" (number 60 could be whatever number) on some pages. Sometimes this happens on some K2 extension pages as well.
The reason causing this error message is, some user added a Joomla article or a K2 item inside the Joomla site, but later this user is deleted from the user management of Joomla by an administrator. So that user ID can not be found by the system. Here we introduce the quickest way to fix it below:
1. Create a super user account on the user management page of your Joomla backend. Please notice you must login with a super admin account to do so.
2. Login to your server PHPMyAdmin, search the name of data table called "#_user", and inside this table change the super user account's ID into the error number you see in the error message.
3. After step 2 is done, go on with this step 3. If your Joomla is 1.5 core, then search table name "#_core_acl_aro" in the PHPMyAdmin, and change that super user's ID into the error number you see in the error message. If your Joomla is 2.5 core, then search table name "#__user_usergroup_map" and change that super user's ID into the error number you see in the error message.
After steps above are all done, you will find the annoying error message is gone.